Cylinder locks



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Filed June 28, 1966 United States Patent 3,349,588 CYLINDER LOCKS John Hines, South Norwalk, Conn., assignor to The New England Lock and Hardware (30., South Norwalk, Conn., a corporation of Connecticut Filed June 28, 1966, Ser. No. 561,219 3 Claims. (Cl. 70-364) This invention relates to improvements in pin-tumbler locks of the kind comprising a cylinder and a key'barrel or plug which is mounted for rotation in the cylinder and when rotated actuates the locking mechanism of the lock. In such locks the cylinder and the plug have cooperating recesses for pin tumblers, drivers and coil springs, and the plug is formed with a key slot. When the proper key is inserted it will position the pin tumblers so that they will contact the drivers respectively at the outer peripheral surface of the plug. With the line of parting between the pin tumblers and the drivers thus positioned the plug is free to rotate as the key is turned.

Experience has shown that this type of lock is not difficult to pick and special tools have been developed for doing it. By means of one tool gentle but steady torsional pressure is exerted on the plug, tending to rotate it, while another tool is inserted in the key slot to lift the pin tumblers one by one and raise the lower ends of the drivers to the line of parting and catch them on the plug surface at the edge of the bores in the plug, one by one. When the lower ends of all the drivers have been raised to the line of parting and caught, at the edge of the plug bores, upon the surface of the plug, a lock of this type has been successfully picked and it is only required to rotate the plug further in unlocking direction to unlock the lock.

An object of the invention is to provide pin-tumbler cylinder locks with means making it more diflicult to succeed in unlocking them by picking.

Another object of the invention is to provide means, out of reach of a picking tool, for re-engaging the cylinder and plug after the lock has been picked.

Another object of the invention is to provide means which will prevent the re-engagin-g means from operating when the proper key is inserted in the key slot.

A further object of the invention is to accomplish the objects stated above without interfering with the positiveness of the normal operation of the lock by the correct key.

This invention will best be understood if the following description is read in connection with the drawing in which:

FIG. 1 is a front elevation of ing the invention,

FIG. 2 is a side elevation the line 2-2 of FIG. 1,

FIG. 3 is a vertical section taken through FIG. 2 showing on a large scale a portion of FIG. 2,

FIG. 4 is similar to FIG. 3 but shows the angular position of the key slot after the lock has been picked and the plug rotated partway toward unlocking position and again interengaging with the cylinder, and

FIG. 5 is a plan view partly cut away showing the a cylinder lock embodypartly in section taken on I relation of the annular grooves 30 to the recesses 18.

In the embodiment of the invention illustrated herein a cylinder has an opening 12 extending through it in which is mounted for rotation a plug 14, the forward end or face of which is flush with the face of the cylinder. A number of bores 16 are provided in the cylinder extending from the opening 12 and in alignment longitudinally of the cylinder. A number of similarly spaced bores 18 are provided in the plug 14, adapted to be aligned with the recesses 16 in the cylinder, when the plug is Patented Oct. 31, 1967 rotated to its position for interlocking with the cylinder. The bores 18 in the plug open at their inner ends into the top of a key slot 19 which extends longitudinally of the plug. Coil springs 20 and driver pins 22 are disposed wholly in the bores 16 respectively of the cylinder, and the tumbler pins 24 and the wafers 26 are disposed wholly in the bores 18 in the plug, when the cylinder recesses 16 are not aligned with the bores 18 in the plug, as when the lock is unlocked. Wafers 26 are disks having an outside diameter substantially equal to the inside diameter of bores 18. When the bores 16 and 18 are axially aligned, as when the lock is locked, the springs 20 push the driver pins 22 toward the plug and they enter partly into bores 18, thus interlocking the plug and cylinder. When no key or other tool is inserted in the key slot 19 the tumbler pins will rest on the bottom of slot 19, but when a key is inserted in slot 19 the pins 24 and the wafers 26 will be raised and will rest on the contoured upper edge of the key, and, depending on the height of the key at the points of contact, one or more of the wafers 26 may be raised partly or entirely into the bores 16 in the cylinder and the upper ends of one or more of the pins 24 may extend partly into the aligned bores 16.

The proper key k for the lock has its upper edge contoured so that the tumbler pins 24 will be disposed entirely within bores 18 and the driver pins 22 and the wafers 26 will be entirely disposed within the bores 16, and the interface between the wafers 26 and the tumbler pins 24 will be at the interface between the cylinder and the plug which is referred to herein as the line of parting. Thus the plug is unlocked from the cylinder and is free to be rotated within the cylinder when the key is turned.

When the bores 18 are out of alignment with the bores 16, the wafers 26 will be wholly contained within bores 16 and their lower ends will contact, and slide over, the surface of the plug 14.

When a wrong key, having a different upper edge contour, is entered in slot 19, one or more of the wafers 26, tumbler pins 24, and driver pins 22 will be moved across the line of parting and so be disposed partly in a bore 16 and partly in a bore 18, and thus will prevent rotation of the plug within the cylinder. 4

In the surface of the plug, preferably on each side of the bores 18, one or more ring-shaped recesse 30 are provided each surrounding an unrecessed portion 31 of the surface of the plug 14, disposed in a line if more than one is employed, each ring-shaped recess 30' being offset from, but aligned with, a bore 18 in a plane normal to the axis of the plug. It will be noted that the centers 31 of the ring-shaped recesses 30 are flush with, and form a part of, the outer surface or periphery of the plug. Ring-shaped recesses 30 could be provided only on one side of the line of bores 18 but as shown herein one or more ring-shaped recesses 30 are provided on each side of the bores 18 to provide a lock which can be used on either right handed or left handed doors. Since the means comprised in the pick resisting means disclosed herein are the same on either side of the bores 18 they are identified herein by the same numerals.

The lower end faces of the driver pins 22 are rcessed or cut out forming annular rims or flanges 23 adapted to enter and engage in ring-shaped recesses 30. The outside diameter of the annular rims or flanges 23 projecting from the lower end of the driver pins, and the outside diameter of the ring-shaped recesses 30, correspond substantially to the inside diameter of the bores 16 and 18. This is important because if the projection at the lower end of a driver pin is substantially less than the diameter of the bore within which it reciprocates the lock will be rendered less positive in its ordinary and intended operation. This results because, if only the reduced lower end portion of a driver pin extends below the line of parting into a bore 18 some relative circumferential movement between the plug and cylinder will be possible. If the projection at the lower end of a driver pin is extremely reduced in diameter some cocking of the wafer which is in contact with the lower end of the pin may result, thus delaying the normal easy unlocking of the lock with the proper key while the key is jiggled in the lock until the wafer is brought into right position to clear the upper end of the bore in the plug and slide over the outer surface of the plug.

If a lock employing a plug with recesses 30 is picked, it is the lower end of the driver pins 22 which are moved onto the surface of the plug while the wafers 26 remain wholly within the bores 18, and the plug can be rotated in its cylinder toward unlocking position until the driver pins 22 are axially in line with the recesses 30 when the flange portions 23 of the pins will enter the recesses 30 respectively and relock the lock. This does not occur when the proper key is inserted in the key slot and the plug is rotated toward unlocking position. When the proper key is inserted in the key slot the wafers 26 are lifted into the bores 16 in the cylinder to bring their lower surfaces to the line of parting and, of course, lifting the driver pins which ride upon them. As the proper key is turned and the plug is rotated the wafers rest on the plug surface and, having a smooth lower surface, they do not become engaged in the recesses 30 but ride over them and, as they are between the plug surface and the driver pins the latter cannot enter the recesses 30, and the plug can be rotated to unlocking position.

When an attempt has been made to pick a lock of the kind described above it cannot be returned to unlocking position even with its correct key. However, users have indicated the protection provided more than offsets the inconvenience experienced when locks have been picked in unsuccessful attempts to unlock them.

There has thus been provided an improved lock in which the above stated objects are accomplished in a thoroughly practical way.

What I claim is:

1. A cylinder lock comprising an annular cylinder, a plug mounted for rotation in the cylinder, a key slot extending axially of the plug, a bore in the plug extending from the periphery of the plug to the top of the key slot, a bore extending into the cylinder from its inner surface and disposed to be in axial alignment with the bore in the plug in locked position, a tumbler pin and a disk-like wafer adapted to be contained within the plug bore, with the tumbler pin below the wafer, the tumbler pin being of sufiicient length to raise the wafer above the line of parting with the lower surface of the wafer in position to slide over the surface of the plug when the proper key is inserted in the key slot, a driver pin and a spring in the cylinder bore, the spring urging the driver pin to move part way across the interface between the plug and cylinder into contact with the wafer in the plug bore, a ring-like recess in the surface of the plug surrounding a portion of the plug surface and circumferentially offset from, and aligned with, the plug bore, said recess having walls generally perpendicular to said plug surface, and adapted to be bridged by the wafer when the plug is turned and the wafer slides over the surface of the plug, the lower end of the driver pin being recessed providing a ring-like flange having the outside diameter of the driver pin and adapted to fit into, and engage in, the ring-shaped recess in the plug surface when the driver pin is placed in direct contact 'With the plug surface due to picking of the lock.

2. The structure claimed in claim 1 in which the lower end of the driver pin defines a concavity surrounded by a ring-shaped projection.

3. The structure claimed in claim 2 in which the recess in the plug surface is a ring-shaped recess and the outside diameter of the recess is substantially equal to the inside diameter of the bores in the cylinder and plug, and the projection at the lower end of the driver pin is an annular projection permitting the lower end of the driver pin to slide over the portion of the surface of the plug which is within the ring-shaped recess in the plug surface and to engage in the recess.

FOREIGN PATENTS 718,164 11/1954 Great Britain. 602,207 2/1960 Italy.

BOBBY R. GAY, Primary Examiner.

EDWARD C. ALLEN, Examiner.

P. TEITELBAUM, Assistant Examiner. 

1. A CYLINDER LOCK COMPRISING AN ANNULAR CYLINDER, A PLUG MOUNTED FOR ROTATION IN THE CYLINDER, A KEY SLOT EXTENDING AXIALLY OF THE PLUG, A BORE IN THE PLUG EXTENDING FROM THE PERIPHERY OF THE PLUG TO THE TOP OF THE KEY SLOT, A BORE EXTENDING INTO THE CYLINDER FROM ITS INNER SURFACE AND DISPOSED TO BE IN AXIAL ALIGNMENT WITH THE BORE IN THE PLUG IN LOCKED POSITION, A TUMBLER PIN AND A DISK-LIKE WAFER ADAPTED TO BE CONTAINED WITHIN THE PLUG BORE, WITH THE TUMBLER PIN BELOW THE WAFER, THE TUMBLER PIN BEING OF SUFFICIENT LENGTH TO RAISE THE WAFER ABOVE THE LINE OF PARTING WITH THE LOWER SURFACE OF THE WAFER IN POSITION TO SLIDE OVER THE SURFACE OF THE PLUG WHEN THE PROPER KEY IS INSERTED IN THE KEY SLOT, A DRIVER PIN AND A SPRING IN THE CYLINDER BORE, THE SPRING URGING THE DRIVER PIN TO MOVE PART WAY ACROSS THE INTERFACE BETWEEN THE PLUG AND CYLINDER INTO CONTACT WITH THE WAFER IN THE PLUG BORE, A RING-LIKE RECESS IN THE SURFACE OF THE PLUG SURROUNDING A PORTION OF THE PLUG SURFACE AND CIRCUMFERENTIALLY OFFSET FROM, AND ALIGNED WITH, THE PLUG 